I can only guess...

I think she's been placed, often, in a no win situation regarding boundaries.

Checking FB. If she shows disapproval, you get upset. So she let it slide and you asked if she could bring pictures. Trying to compromise she brought them. Now you wanted her to share more about her. She denied, you got upset. She called back to show that she wasn't rejecting or abandoning you, but made a comment that got you upset, again.

It would feel like no matter what, she can never do enough, be enough, care enough. Regardless of whether or not she complies with your request, there is always wanting more. And when she puts a boundary in place, is told that it's still not enough and she is met with anger or frustration.

She is trying to stay within the bounds of her profession (therapy is not about her, her life, her husband, her kids, her pets, etc) but when she tries, she loses and has to do damage control.

I think you push her buttons because she DOES care so deeply. She WANTS to help. But in the end she is just one person, who cares very much, but has to stay within guidelines so that you get the care you need. And to feel like she constantly falls short, can certainly make one feel upset.

Again, just guessing...